Motor vehicles are equipped with ventilation and/or air conditioning systems, particularly in order to be able to regulate an air temperature in a passenger compartment of a motor vehicle. For this purpose, a corresponding system comprises air vents, each of which serve for introducing an air flow directly into the passenger compartment. The air vents may be arranged, for example, on a dashboard, a center console or in the footwell of the passenger compartment. The air vents may be supplied with air either individually or in groups and may comprise means of adjustment for adjusting the direction and/or strength of the air flow emerging from each of the vents.
A known method for registering the state of a ventilation and/or air conditioning system of a motor vehicle is to connect a measuring device for measuring a parameter of an air flow via an air duct passage to an air vent and to measure the parameter during operation of the ventilation and/or air conditioning system. On the basis of the measured parameter it is possible to assess whether the ventilation and/or air conditioning system is functioning correctly. For example, it can be determined whether a blower of the ventilation and/or air conditioning system is producing a specific output and/or whether the air flow flowing to the air vent is being diminished, for example, by a fouled air filter or the like. If this is the case, servicing of the ventilation and/or air conditioning system is required.
A precise measurement of a parameter of an air flow emerging from an air vent of a motor vehicle is normally not possible by conventional means. In particular, the measurement may be adversely affected due to any leakage of air occurring and/or due to turbulence occurring as a result of flow edges present in the air duct passage.
U.S. Pat. No. 6,107,923 A discloses a device for registering the state of an air filter in a heating and/or air conditioning system for the interior of a motor vehicle. The device comprises a sensor for use on the outlet of an air vent of the system, in order to register the emerging air flow, together with a measuring device connected to the sensor for measuring a parameter of the air flow. The sensor comprises a housing, which has a contact face of a shape matched to the shape of the air vent, and an outlet aperture, which is connected to the measuring device by means of a flexible pipe or a flexible duct. The housing is detachable from the pipe or the duct. The outline of the contact face is provided with a deformable coating, which is impermeable to air and made from foam plastic, for example.
WO 2004/063676 A1 relates to a portable air flow sensor for measuring the amount of air delivered from a ventilation unit. The portable air flow sensor is capable of measuring the air flow of a vehicle air conditioning duct system accurately and rapidly. The portable air flow sensor comprises a fan for cooling a computer CPU.
KR 2015/0005100 A relates to a portable digital volumetric air flow measuring device having a seal structure. The portable digital volumetric air flow measuring device comprises: a cylindrical housing, in which an inlet cover and a housing are arranged; a flexible duct, which connects the cylindrical housing to a ventilation unit; an air cleaner which is installed in the inlet cover in order to clean the air; and a measuring element which measures the volume of air passing through the air cleaner. In addition, the portable digital volumetric air flow measuring device comprises a front nozzle cover having a cover coupling channel, into which the inlet cover is inserted, and a first seal insertion channel, into which a number of sealing elements are adhesively inserted. It further comprises a rear nozzle cover having a seating channel, in which an outer peripheral flange of the measuring element is seated. It further comprises a housing insertion channel, into which the housing is inserted. It further comprises a second seal insertion channel, into which a number of sealing elements are inserted; and a sealing element, in which multiple nozzle sealing elements, adhesive elements and body parts are contained, in order to improve the cohesion, by increasing the adhesion between the front nozzle cover and the rear nozzle cover on both surfaces of the outer peripheral flange.
CN 102 235 386 A discloses an air flow drive device having a deflector element, an air flow receiver, a first aperture and a second aperture, the first aperture and the second aperture ducting the air flow. The aperture area of the first aperture differs from that of the second aperture and the air pressures of the first aperture and the second aperture have a differential value, so that the differential value can be used to calculate the rate of flow in the air flow drive device.
JP S6 113 112 A discloses an air flow rate measuring instrument, in which a static pressure detector for registering a mean static pressure is arranged in an air collector hood. An aperture of the air collector hood is applied to a diffusion aperture in the cover. A pitot tube for registering a static pressure is provided in the air collector hood, in order to register a mean static pressure in the hood. The hood is moreover provided with a connecting pipe, in order to register a mean total pressure by means of a pitot tube. At the bottom end of the connecting pipe a fan is provided. The fan adjusts a variable blower, so that the static pressure in the hood can be equal to that of the chamber. The mean static pressure is then subtracted from the mean total pressure, in order to calculate the mean dynamic pressure, from which the volume of air is determined.